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Método Hashtable.Contains (Object)

 

Publicado: octubre de 2016

Determina si Hashtable contiene una clave específica.

Espacio de nombres:   System.Collections
Ensamblado:  mscorlib (en mscorlib.dll)

public virtual bool Contains(
	object key
)

Parámetros

key
Type: System.Object

Clave que se buscará en la interfaz Hashtable.

Valor devuelto

Type: System.Boolean

true si la colección Hashtable contiene un elemento con la clave especificada; en caso contrario, false.

Exception Condition
ArgumentNullException

El valor de key es null.

Contains implements IDictionary.Contains. It behaves exactly as ContainsKey.

This method is an O(1) operation.

Starting with the .NET Framework 2.0, this method uses the collection’s objects’ M:System.Object.Equals(System.Object) and M:System.IComparable.CompareTo(System.Object) methods on item to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the M:System.Object.Equals(System.Object) and M:System.IComparable.CompareTo(System.Object) methods of the item parameter on the objects in the collection.

The following example shows how to determine whether the T:System.Collections.Hashtable contains a specific element.

using System;
using System.Collections;
public class SamplesHashtable  {

   public static void Main()  {

      // Creates and initializes a new Hashtable.
      Hashtable myHT = new Hashtable();
      myHT.Add( 0, "zero" );
      myHT.Add( 1, "one" );
      myHT.Add( 2, "two" );
      myHT.Add( 3, "three" );
      myHT.Add( 4, "four" );

      // Displays the values of the Hashtable.
      Console.WriteLine( "The Hashtable contains the following values:" );
      PrintIndexAndKeysAndValues( myHT );

      // Searches for a specific key.
      int myKey = 2;
      Console.WriteLine( "The key \"{0}\" is {1}.", myKey, myHT.ContainsKey( myKey ) ? "in the Hashtable" : "NOT in the Hashtable" );
      myKey = 6;
      Console.WriteLine( "The key \"{0}\" is {1}.", myKey, myHT.ContainsKey( myKey ) ? "in the Hashtable" : "NOT in the Hashtable" );

      // Searches for a specific value.
      String myValue = "three";
      Console.WriteLine( "The value \"{0}\" is {1}.", myValue, myHT.ContainsValue( myValue ) ? "in the Hashtable" : "NOT in the Hashtable" );
      myValue = "nine";
      Console.WriteLine( "The value \"{0}\" is {1}.", myValue, myHT.ContainsValue( myValue ) ? "in the Hashtable" : "NOT in the Hashtable" );
   }


   public static void PrintIndexAndKeysAndValues( Hashtable myHT )  {
      int i = 0;
      Console.WriteLine( "\t-INDEX-\t-KEY-\t-VALUE-" );
      foreach ( DictionaryEntry de in myHT )
         Console.WriteLine( "\t[{0}]:\t{1}\t{2}", i++, de.Key, de.Value );
      Console.WriteLine();
   }

}


/* 
This code produces the following output.

The Hashtable contains the following values:
        -INDEX- -KEY-   -VALUE-
        [0]:    4       four
        [1]:    3       three
        [2]:    2       two
        [3]:    1       one
        [4]:    0       zero

The key "2" is in the Hashtable.
The key "6" is NOT in the Hashtable.
The value "three" is in the Hashtable.
The value "nine" is NOT in the Hashtable.

*/ 

Plataforma universal de Windows
Disponible desde 10
.NET Framework
Disponible desde 1.1
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